Schedule H

Oral

• Prolonged-release tablets: 7.5 mg, 15 mg

INDICATIONS + DOSING — FOR CLINICIAN USE ONLY

Primary Indications (Approved / Standard in India)

⮞ Overactive Bladder (OAB) with urinary urgency, frequency, and/or urge incontinence

Parameter Recommendation

Starting dose 7.5 mg once daily (with or without food)

Titration May increase to 15 mg once daily after ≥2 weeks if inadequate response and drug is tolerated

Usual maintenance dose 7.5–15 mg once daily

Maximum dose 15 mg once daily

Clinical Notes:

• Swallow tablets whole; do not crush, chew, or break

• Onset of symptomatic improvement may take several days; optimal benefit typically achieved within 2–4 weeks

• Extended-release formulation reduces peak anticholinergic adverse effects

• Not effective for stress urinary incontinence — confirm diagnosis before prescribing

Secondary Indications — Adults Only (Off-label)

Not applicable.

No established off-label indications are routinely used in Indian specialist practice.

PAEDIATRIC DOSING (Specialist Only)

Primary Indications (Approved / Standard in India)

Not applicable — darifenacin is not approved for use in patients under 18 years of age.

Secondary Indications — Paediatric Doses (Off-label)

Not applicable.

Safety Statement:

Safety and efficacy have not been established in the paediatric population. Use in children and adolescents under 18 years is not recommended, even under specialist supervision.

30 (Mild to moderate impairment) No dose adjustment required

<30 (Severe impairment) Use with caution; limit to 7.5 mg/day; monitor for anticholinergic adverse effects

End-stage renal disease / Dialysis Avoid use — insufficient data; specialist supervision only if essential

• Known hypersensitivity to darifenacin or any excipient in the formulation

• Urinary retention or significant bladder outlet obstruction

• Gastric retention or severe decreased gastrointestinal motility (e.g., paralytic ileus)

• Uncontrolled narrow-angle glaucoma

• Severe hepatic impairment (Child-Pugh C)

• Myasthenia gravis

• Elderly patients — increased risk of confusion, constipation, urinary retention

• Pre-existing constipation or gastrointestinal obstructive disorders

• Autonomic neuropathy

• Controlled narrow-angle glaucoma — monitor closely

• Patients with bladder outflow obstruction (not severe enough to be contraindicated) — risk of urinary retention

• Concurrent use with other anticholinergic agents — additive anticholinergic burden

• Gastroesophageal reflux disease — may worsen due to reduced GI motility

• Cognitive impairment or dementia — may exacerbate symptoms

• Hot weather or fever — impaired sweating response

Parameter Details

Safety category Limited human data; animal studies do not show teratogenicity

Use in pregnancy Only if potential benefit clearly outweighs risk; not first-line

Preferred alternatives Behavioural therapy (bladder training, pelvic floor exercises); topical oxybutynin if pharmacotherapy essential

Monitoring Maternal anticholinergic side effects; fetal growth

Parameter Details

Compatibility Not recommended — insufficient human data

Expected levels in milk Likely low (high protein binding ~98%) but uncertain

Preferred alternatives Behavioural therapy; oxybutynin with caution if drug therapy required

Infant monitoring Poor feeding, constipation, sedation, irritability

Parameter Recommendation

Starting dose 7.5 mg once daily

Titration Slow; increase to 15 mg only if clearly needed and well tolerated

Special risks Dry mouth, constipation, confusion, cognitive decline, urinary retention, falls

Additional considerations Assess baseline cognitive function; evaluate total anticholinergic burden from other medications; consider falls risk in frail patients

Interacting Drug/Class Effect Management

Potent CYP3A4 inhibitors (ketoconazole, itraconazole, ritonavir, nelfinavir, clarithromycin) Significant increase in darifenacin plasma levels Limit dose to 7.5 mg/day; avoid co-administration if possible

CYP2D6 substrates with narrow therapeutic index (flecainide, thioridazine, tricyclic antidepressants) Darifenacin inhibits CYP2D6 → increased substrate levels Monitor for toxicity; consider dose reduction of substrate

Other anticholinergics (oxybutynin, tolterodine, tricyclic antidepressants, antihistamines, antipsychotics) Additive anticholinergic effects — dry mouth, constipation, confusion, urinary retention Avoid concurrent use if possible; assess total anticholinergic burden

Interacting Drug/Class Effect Management

Moderate CYP3A4 inhibitors (erythromycin, fluconazole, diltiazem, verapamil) Modest increase in darifenacin levels Use caution with 15 mg dose; monitor for adverse effects

CYP3A4 inducers (rifampicin, carbamazepine, phenytoin, phenobarbital) May reduce darifenacin plasma levels and efficacy Monitor for reduced symptom control

Digoxin Slight increase in digoxin levels possible Monitor digoxin levels, especially in elderly or renal impairment

Metoprolol (CYP2D6 substrate) Possible increase in metoprolol levels Monitor for bradycardia and hypotension

• Dry mouth (most common)

• Constipation

• Dyspepsia

• Abdominal pain

• Nausea

• Headache

• Dry eyes

• Blurred vision

Adverse Effect Clinical Action

Urinary retention Discontinue drug; may require catheterisation

Acute angle-closure glaucoma Ophthalmic emergency — immediate discontinuation and urgent ophthalmology referral

Hallucinations / Acute confusion More common in elderly; discontinue and evaluate

Severe constipation / Paralytic ileus Discontinue immediately; supportive management

Angioedema (rare) Discontinue; do not re-challenge

After initiation (2–4 weeks) Symptom response; tolerability; constipation; cognitive changes

Long-term Periodic assessment of anticholinergic burden; cognitive function in elderly; symptom control; constipation; residual urine volume if indicated

• Dariten (Sun Pharma)

• Daritol (Cipla)

• Enablex (Abbott Healthcare)

Note: Fixed-dose combinations are not routinely available or recommended.

7.5 mg prolonged-release tablet ₹20–₹35 per tablet

Note: Not under NPPA price control. Not listed in NLEM.

• M3 selectivity advantage: Darifenacin has relatively higher selectivity for M3 receptors over M1 — theoretically less impact on cognition compared to non-selective antimuscarinics; may be preferred in elderly with cognitive concerns

• Constipation management: Evaluate baseline bowel function before initiation; advise increased fluid and fibre intake; consider laxatives if needed

• Differentiate incontinence type: Darifenacin is effective only for urge incontinence and OAB; not indicated for stress urinary incontinence — accurate diagnosis is essential

• Hepatic dose cap: Never exceed 7.5 mg/day in moderate hepatic impairment (Child-Pugh B) or when co-administered with potent CYP3A4 inhibitors

• CYP2D6 inhibition: Be aware of interactions with narrow therapeutic index drugs metabolised by CYP2D6 (e.g., flecainide, some antidepressants)

• Anticholinergic burden: Always assess cumulative anticholinergic load when prescribing in elderly — multiple anticholinergic medications significantly increase risk of cognitive decline and delirium

darifenacin; overactive bladder; OAB; antimuscarinic; M3-selective; urge incontinence; elderly-caution; hepatic-adjust; anticholinergic; urinary retention risk

RxIndia v1.0 — 09 Jan 2025

• CDSCO approved product information

• Indian Pharmacopoeia / National Formulary of India

• API Textbook of Medicine

• Goodman & Gilman's The Pharmacological Basis of Therapeutics (pharmacology reference)

• AIIMS Hospital Drug Formulary

• Manufacturer product inserts (India)